A mobile communications network is typically made up of a plurality of cells. Each cell includes a radio base station, with each base station connected to a mobile switching center or a packet service node that manages communications sessions between mobile stations and terminals coupled to a public switched telephone network (PSTN) or a packet-based data network. Communications between mobile stations and base stations are performed over wireless links.
Traditional wireless protocols provide for circuit-switched communications. Such protocols include time-division multiple access (TDMA) protocols and code-division multiple access (CDMA) protocols. In a circuit-switched network, a channel portion between two endpoints (e.g., two mobile stations) is occupied for the duration of the connection between the endpoints.
However, with the wide availability of the Internet and intranets, packet-switched communications (e.g., web browsing, electronic mail, and so forth) have become more common. Generally, a circuit-switched connection is an inefficient technique for communicating packet data. As a result, third generation (3G) and beyond wireless technologies are being developed and implemented to provide higher bandwidth and more efficient packet-switched communications (of data as well as voice and other forms of real-time data) over wireless networks.
One example of a packet-switched wireless technology is defined by the CDMA 2000 family of standards, developed by the Third Generation Partnership Project 2 (3GPP2). A CDMA 2000 wireless communications network is capable of supporting both circuit-switched services and packet-switched services. For TDMA, packet-switched wireless communications protocols have also been developed, such as the Enhanced General Packet Radio Service (EGPRS) protocol as defined by the 3GPP (Third Generation Partnership Project) UMTS (Universal Mobile Telecommunications System) Release 1999 Standard, and others.
In packet-switched communications, packets that are sent across a data network are routed based on a source network address and a destination network address contained in each packet. In one example, packets sent over a packet-based data network are defined by the Internet Protocol (IP).
Once a packet data session is established between a mobile station and another end device, communications of packet data can occur between the mobile station and the other end device. Typically, in response to a teardown request, the packet data session is terminated. CDMA 2000 provides an always-on feature that is intended to maintain a subscriber's packet data session on a data network so that the mobile network does not initiate release of the subscriber's packet data session unless the mobile network determines that the subscriber is no longer reachable. However, an efficient messaging mechanism has not been provided to handle the release of an always-on mobile station.